1. Field of the Invention
The present invention relates to an optical composition for a multi-color display that makes use of a periodic structural body and a manufacturing method thereof. In addition, the present invention relates to an optical element that is applied in, for example, a display element or a light control element and a displaying method thereof.
2. Description of the Related Art
In recent years, displaying and color controlling devices that use color generation mechanisms based on “structural color” that utilizes a sub-micro scale periodic structural body (regular structural body) have been proposed. To date, color generation of structural colors that use periodic structural bodies utilizing colloidal crystals that use monodispersed fine particles of silica or a polymer, a micro-domain structure of a block copolymer, and a lamellar structure of a surfactant have been reported.
In particular, there are many reports on periodic structural bodies utilizing colloidal crystals, and they can be categorized into two kinds of structural bodies, namely, a loosely-packed type that makes use of the repulsive force between particles, and a closest packed type where particles are closely packed.
For example, there is a proposal where a colloidal crystal is fixed in a stimulation-responsive gel, a stimulation is inputted to alter the degree of swelling of the gel, so that a structural color is altered (for example, (1) K. Lee, S. A. Asher, J. Am. Chem. Soc., 122, 9534 (2000)).
Furthermore, a color control that makes use of an oxidization/reduction reaction of a matrix that fixes a colloidal crystal (for example, (2) T. Iyoda, et al., Polymer Preprints, Japan, 50 (3), 472 (2001)), and a color control due to swelling/refractive index variation owing to addition of a solvent (for example, (3) H. Fudouzi and U. Xia, Adv. Mater., 15, 892-896(2003)) are reported as well. Still furthermore, a display that uses a decolorization-color generation system of the structural color by means of contact-peeling by applying an electrical field to a laminated film is also proposed (for example, (4) a document of Iridigm Corp (USA)).
The structural colors in these proposals do not use dyes or pigments, but make use of the dielectric characteristics of a material being used and the reflection of a particular wavelength originating from a mesoscale structure; accordingly, it is considered the most effective method when multi-colors are emitted with a single element.
However, in the above-mentioned documents 1 through 3, since, the magnitude of a display site itself varies with variations in the degree of swelling of the gel, and since almost all colloidal crystals are electrically inactive, it is difficult to apply these methods to display elements under the present circumstances. Furthermore, in the document 4, although it is a display that carries out the decolorization and the color generation based on an electrical drive, it can perform only one of two ways of decolorization and color generation and cannot display multi-colors. That is, under the present circumstances, the characteristics of structural colors are not being fully utilized. Furthermore, according to these proposals, it is also difficult to realize color generation (display) having memory properties.